DESCRIPTION (Investigator's Abstract): Acetylcholinesterase (AChE), well known for hydrolyzing acetylcholine (ACh) at the cholinergic synapse, is also present at non-cholinergic sites. Evidence is emerging for AChE's non-catalytic role during neuronal development, regeneration and aging. Our findings show that AChE in Aplysia hemolymph as will as human AChE promote neurite regeneration in primary cultures of adult Aplysia neurons and this action appears to be mediated by AChE's carbohydrate and peripheral anionic sites. The long term goals of this research are to understand the mechanism of the non-catalytic action of AChE as a growth factor in the nervous system. Aplysia, a marine a=mollusc, is a ideal model to study this novel function aAChE since adult Aplysia neurons with known function can be successfully cultured and morphological and biochemical findings can be readily correlated with physiological and behavioral effects. Based on preliminary results, using in vitro and in vivo techniques, the objectives of this proposal are to test 1) that AChE promotes neurite growth through its peripheral anionic site and not by its catalytic site using site-specific inhibitor and site-altered mutant AChE; 2) that AChE binds to a neuronal mannose receptor in a calcium dependent manner through its carbohydrate moiety using labelled AChE and determining receptor binding with sugar binders blockers and calcium chelators; 3) that the peripheral anionic site binds to calcium and thus facilitates AChE receptor binding by examining he effects of calcium binding to peripheral site on recaptor binding; 4) that AChE promotes neurites regeneration i vivo by correlating AChE levels to nerve regeneration in the freely behaving animals; and 5) to identify, separate and characterize the AchE-receptor as a first step to understand the intraneuronal events triggered by AChE inpromoting neurite growth. These studies will begin to unravel AChE's novel mechanism of action as a neuronal growth factor. Understanding the full repertoire of AChE's functions uncritical, especially in view of AChE's possible, significant non-cholinergic roles in age=related neurodegenerative disease and in view of the therapeutic use anticholinesterase in cholinergic disease and a insecticides in agriculture.